Crystal point detonation fuze



June 30, 1959 c. F. BROWN ET AL 2,892,411

CRYSTAL POINT DETONA'IiION FUZE Fil ed D60. 6. 1951 INVENTORS c. F. BR

KMQA & MM AM A TTYS.

CRYSTAL POINT DETONATION FUZE Calvin F. Brown, West Friendship, and Peter F. Vial, Silver Spring, Md.

Application December 6, 1951, Serial No. 260,295

8 Claims. (Cl. 102-402) (Granted under Title 35, US. Code (1952), sec. 266) This invention relates to a fuze and more particularly to an impact responsive device composed of barium titanate for use in a VT fuze for initiating an explosive charge arranged within an ordnance missile such, for example, as a projectile, rocket or bomb and in which the firing is accomplished by a voltage developed within the device upon impact of the missile with a target.

The VT principleof fuzing makes possible the detonation of explosive ordnance in such a position upon ap proach to a target that maximum fragmentation damage is obtained. Fuzes utilizing this principle of operation initiate detonation by electrical interaction involving closeness of the target, and rate of approach of the fuze to the target, both necessarily being present to a certain definite degree before the fuze operates. Fuzes of this type are not adaptable for close range purposes such, for example, when employed against low flying airplanes or when dropped from a low flying plane toward a target for the reason that the time interval and distance required to permit the VT system to complete its cycle of operation is insuflicient to arm the fuze and cause it to function in the usual manner and thus rendering the missile useless against such target.

The presentinvention contemplates the provision of a new and improved impact firing means for use in a VT or electric type fuze wherein means are provided for functioning the fuze and exploding the missile upon impact of the missile with a target regardless of the condition of the VT system employed therewith and in which a polarized piezoelectric element composed of barium titanate is employed for producing a voltage sufficiently high to fire an electroresponsive detonator regardless of the thinness of skin of the target.

An object of the present invention is to provide a new and improved impact responsive device for a fuze employed in the nose of an ordnance missile and adapted to 'fire and explosive charge arranged within themissile by a voltage developed as a disc type piezoelectric element composed of barium titanate is compressed in response to the impact of the nose with a thin skinned target.

Another object is to provide a new and improved impact responsive means for a fuze adapted for use in an ordnance missile in which a polarized piezoelectric element is employed for firing the explosive charge arranged therein in response to a voltage produced thereby when the fuze is in an armed condition and the missile is subjected to a slight shock or deceleration upon impact with a target. I

Another object is to provide a new and improved firing unit for a fuze adapted for use in an ordnance missile and in which a polarized piezoelectric element composed of barium titanate is employed as a source of electrical energy for firing an electro-responsive detonator as the missile strikes a target.

A still further object is to provide a new and improved firing unit for a fuze operable in response to impact suflicient to cause a slight deceleration of the missile during flight and which is economical to manfacture, reliable in ice operation and which possesses all the qualities of ruggedness and dependability in service.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. 1 is a fragmentary view of a projectile and nose fuze therefor, the fuse casing being partly broken away and in section for the purpose of more clearly disclosing the firing unit of the present invention;

Fig. 2 is an enlarged fragmentary sectional view of the nose of the projectile showing the arrrangement of the firing unit therein in accordance with a preferred embodiment of the invention;

Fig. 3 is an enlarged sectional view of the firing unit of Fig. 1;

Fig. 4 is a view in diagrammatic form of an electrical circuit and instrumentalities suitable for use with the firing unit of Fig. 1; and

Fig. 5 is an alternative arrangement of the firing unit of Fig. 1.

Referring now to the drawings and more particularly to Fig. 1 there is shown thereon a projectile generally indicated by the numeral 10 and having a fuze 11 of the type known to those skilled in the art as a VT fuze secured thereto as by pressing into the conventional cavity thereof and comprising a crushable nose portion 12 preferably composed of any plastic material suitable for the purpose such, for example, as Teflon or polyethylene.

As more clearly shown on Fig. 2 a polarized piezoelectric element generally indicated by the reference character 13 is arranged within the nose 12 and encased in suitable plastic material 14, the element comprising a disc 15 composed of fuzed metallic titanate such, for example, as barium titanate and having the essential characteristic of remaining stable with respect to sensitivity thereof over a long period of time whereupon the piezoelectric properties of the element is maintained substantially constant.

The element 13 has secured to opposite faces thereof respectively a pair of collecting electrodes 16 and 17, the electrodes being composed of any material suitable for the purpose, such, for example, as silver or the like. As more clearly shown in Fig. 2, the electrode 16 is enclosed within and in abutting engagement with the plastic material 14, the electrode 17 being in abutting engagement with a support 18 composed of suitable plastic material. By the aforesaid arrangement of the crystal 13 impact of the missile with a thin skinned target such, for example, as an aircraft, the nose 12 will be crushed sufficiently to cause the crystal 13 to be compressed between the plastic material 14 and support 18 whereupon a voltage is developed in the crystal suflicient to operate the fuze and thus explode the missile. The arming and electrical interaction firing arrangement employed with the point detonating firing unit of the present invention and disposed in the fuze body 11 may be of any conventional construction or similar to the structure disclosed in US. Patent 2,856,852. It will be further understood that the fuze'is adapted to be maintained in a safe or unarmed condition during handling and transportation by any of the conventional instrumentalities now employed in VT fuze systems whereupon arming of the fuze will not occur until the missile has been fired from a gun and traveled a predetermined distance from the gun muzzle, from an aircraft in flight or a launching rack, as the case may be.

As more clearly shown on Fig 3, the crystal 13 is provided with a centrally disposed bore 19 having arranged therein a sleeve 21 composed of any material suitable for the purpose such, for example, as Bakelite or the like, the sleeve extending through a complementary aper turc 22 formed in the electrode 17 and terminating a predetermined distance beyond the electrode 17 as at 20. Arranged on the portion 20 of the sleeve 21 and secured to the electrode 17 in any suitable manner such, for example, as by soldering theparts together as at .23. Fig. 3, is a coaxial cable 24 having a centrally disposed conductor .25 arranged therein and extending therethrough and through the sleeve 21, .the cable being disposed within abore 26 formed in the support .18.

In view of the foregoing and withgparticular reference to Fig. 4 it will now be apparent that an electrical circuit arrangement is provided from the crystal 13 to the detonator 27 by way of electrode 16, conductor 25 to one terminal of the detonator, through the bridge wire of the detonator to the other terminal thereof and thence to electrode 17 by the way of cable 24. However, the detonator is normallyshorted byany suitable means such, for example, as a fine wire or frangible .element 28 connectedacross cable 24 and conductor 25, Fig. 4, and remains shorted until the wire is severed in any conventional manner such, for example, as by the usual inertial actuated plunger arrangement 29 adapted to be forcibly vdriven into engagement therewith in response to a :set back force applied thereto as the missile is fired from a gun -or launching rack, as the case may be.

When the wire 28 is severed in the aforesaid manner the firing circuit to the detonator 27 is rendered effective and upon impact of the missile with the target the .nose 12 will be crushed as the forwardmotion of the missileis suddenly arrested whereupon the plastic material 14 is urged forcibly against the crystal 13. When this occurs the crystal is compressed between the members 14 and 18 thereby causing a voltage to be generated in the crystal in proportion to the rate of increase in pressure applied thereto, the voltage being of sufiicient intensity to fire the detonator 27 thereby initiating explosion of the main charge 31 arranged within the shell 32, Fig. 1, regardless of thethickness of skin of the target body.

Referring now to Fig. of the drawings there is shown thereon an alternative arrangement of the device of Fig. 1. In this arrangement the cable 24 is bent substantially at a right angle as at 33 .and secured to the electrode 17 as by soldering the parts together along a line .of contact indicated by the numeral 34, the portion 33 of the cable terminating short of the outer edge portion .of the crystal 13 and having the centrally disposed conductor 25 .thereof extending therefrom and secured to the electrode 16 as at 35.

From the foregoing, it will be understood that a .new and improved point detonating element has been devised for use in at VT fuze wherein the element comprises a polarized piezoelectric disc composed of barium titanate and disposed within a crushable nose portion of a fuze for providing a source of energy for functioning an electroresponsive detonator arranged therein upon impact of the missile with a target, in which'means including a pair of collecting electrodes operatively connected to the crystal and detonator provide means for collecting and transferring a voltage developed within the crystal as the crystal is compressed in responseto the impact of the missile with the target, thevoltage being of sufiicient value to fire the low energy detonator, and in which electrical shorting means is provided for maintaining the firing circuit in a safe condition until the shorting means has "been actuated to an unshorted condition during flight of the missile.

Whereas the invention has been described'in detail with respect to a projectile, it will be understood that it may be advantageously employed, if desired, with-a rocket or bomb. While-the device has been shown andparticularly described in connection with an inertial controlled safety switching means including a severable wire, it will be understood that any conventional safety means may be employed such, for example, as a mercury switch for maintaining the firing circuit inactive and the fuze in a safe condition until the missile has been fired, launched or dropped as the case may be.

If desired, the safety feature may be obtained by the use of either mechanical or electrically controlled means or both by having a circuit arrangement whereby the detonator is disposed in an open circuit when the fuze is in a safe condition, and the circuit to the detonator will remain open until the fuze has been actuated to a closed or armed condition by either setback, setforward, or-centrifugal force.

From the foregoing description it will be apparent that a new and improved electric point detonating element has been devised for use in a VT fuze wherein the firing element is primarily adapted to function the fuze and explode the missile upon impact of the missile -with:a target regardless of thinness of skin of the target or the condition of the conventional instrumentalities for firing the fuze by electric interaction involving closeness of the target, and rate of-approach of the fuze to the target.

Obviously many modifications and variations of the present invention are possible in the light .of the .above teachings. It is therefore to be understood that Within the scope of the appended claims the invention may be practiced otherwise than specifically described.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon .or therefor.

What is claimed as new and desired to be secured by Letters Patent is:

l. A device of the character disclosed comprising an electroresponsive detonator, a crushable casing, a piezoelectric element fixedly encased within said casing for generating a voltage sufficient to fire the detonator when said element is compressed in response to crushing of said casing, and circuit means connected to said element and to said detonator for firing said detonator by said voltage.

2. A device of the character disclosed for firing an electroresponsive detonator comprising a casingcrushable in response to a sudden shock received thereby, a quantity of plastic material disposed within said casing and movable in response to the crushing of said casing, and a metallic titanate element arranged within said plastic material for generating a voltage sufiicient to fire the .deto nator when said element is compressed as said plastic material is forcibly urged thereagainst in response .to the crushing of said casing.

3. A device of-the character disclosed for firing an electro-responsive detonator arranged with a fuze casing, means including a nose secured to said casing constructed and arranged to be crushed in response to a sudden slight shock received thereby, a barium titanate crystal arranged within the casing for generating a voltage sufiicient to fire the detonator when said crystal is compressed in response to the crushing of said nose, and means on'said crystal for collecting said voltage as the crystal is compressed.

4. A device of'the character disclosed for firing an electro-responsive detonator arranged within a fuze casing, means including a yieldable nose secured 'to said casing and movable in response 'to a sudden shock received thereby, a piezoelectric crystal composed .of metallic titanate arranged within the nose for generating a voltage of suificient intensity to fire the detonator when .said crystal is compressed in response to .the movement of said responsive means, and means including a pair of electrodes on said crystal and operatively connected to said detonator for transferring said voltage to the detonatoras said crystal is compressed.

5. A device of the character disclosed for firing an electro-responsive detonator arranged within a fuze casing,

means including a crushable nose secured to said casing and crushed in response to a sudden .shock received therecrushing of said nose, an electrode secured to one surface of said crystal, a second electrode secured to the other surface of the crystal, and circuit means secured to said electrodes and operatively connected to the detonator for transferring said voltage to the detonator as said crystal is compressed.

6. In a firing unit for a fuze, in combination, an ordnance missile, a casing for said missile, an explosive charge arranged within said casing, electroresponsive means for detonating said charge, a nose member secured to said casing and crushable in response to the impact of the missile with the thin skin of a target, and means including a crystal composed of barium titanate fixedly encased within said nose member and electrically connected to the detonating means for generating a voltage sufiicient to fire said electroresponsive means as said crystal is compressed in response to the crushing of said nose.

7. In a firing unit for a fuze, in combination, an ordnance missile, a casing for said missile, an explosive eharge arranged within said casing, a housing for said fuze secured to said casing, a nose secured to said housing and crushable in response to the impact of the missile with the thin skin of a target, means including a mass of barium titanate arranged within said nose and responsive to the pressure applied thereto as the nose is crushed thereagainst in response to said impact for generating an electrical impulse, a normally inactive firing circuit connected to said impulse generating means, means responsive to an inertial force applied thereto for rendering said firing circuit active, and an electroresponsive detonator included within said firing circuit for firing said explosive charge in response to said impulse when the firing circuit has been rendered active and upon said impact.

8. In a firing unit for a projectile adapted to be fired from a gun toward a target, in combination, a casing, an explosive charge arranged within said casing, a nose on said casing and crushable in response to the impact of the projectile with said target, a crystal element composed of barium titanate arranged Within said nose and responsive to the pressure applied thereto as the nose is crushed thereagainst in response to said impact for gen erating an electrical impulse, a normally inactive firing circuit connected to the crystal element, frangible means included within said firing circuit for rendering the firing circuit inefiective until the frangible means is severed in response to a sudden blow received thereby, plunger means responsive to the set back force applied thereto as the projectile is fired from said gun for severing said frangible means as the plunger is driven into engagement therewith, and an electroresponsive detonator included with said circuit for firing said explosive charge in response to said impulse when said frangible means is severed and upon said impact.

References Cited in the file of this patent UNITED STATES PATENTS 

